Gasoline Direct-injection Compression-Ignition (GDCI) is an engine combustion process that shows promise in improving engine emissions performance and efficiency. GDCI provides low-temperature combustion for high efficiency, low NOx, and low particulate emissions over the complete engine operating range. Low-temperature combustion of gasoline may be achieved using multiple late injection (MLI), intake boost, and moderate EGR. GDCI engine operation is described in detail in U.S. Patent Application Publication No. 2013/0213349A1, the entire contents of which are hereby incorporated herein by reference.
The autoignition properties of gasoline-like fuels require relatively precise control of the thermal state within each combustion chamber to achieve compression ignition and to maintain robust combustion in each individual cylinder of a multiple-cylinder engine. Since there is no spark to initiate the combustion process, the in-cylinder conditions must be correct for auto-ignition. A system and method for conditioning intake air to a GDCI engine is described in U.S. Patent Application Publication No. 2013/0298554A1, the entire contents of which are hereby incorporated herein by reference.
In order to save fuel, it is known to implement engine stop-start strategies, in which the engine is stopped when the vehicle is stopped (i.e. when the engine would otherwise be operated at idle speed), and restarted when vehicle motion is desired. To improve starting performance of a GDCI engine, it is often desirable to increase the temperature of the intake air charge to the engine while starting, as described in U.S. patent application Ser. No. 14/068,278 titled “COLD START STRATEGY AND SYSTEM FOR GASOLINE DIRECT INJECTION COMPRESSION IGNITION ENGINE”, the entire contents of which are hereby incorporated herein by reference. Conventional means for increasing intake air temperature such as electric heaters are relatively slow, making them impractical for start-stop operation of a GDCI engine. Accordingly, an alternative way to provide heat to the intake air charge usable during start-stop operation is desired.